(1) Field of the Invention
The present invention relates to a flanged valve, more particularly to a flanged valve having flanges on the ends thereof for connection with pipes in a pipe line.
(2) Description of the Related Art
Flanged valves, especially flanged plastic gate valves connected with transport pipe lines for clean and sewage water, irrigated water, chemicals, foods and the like, are disclosed in Japanese Unexamined Utility Model Publication No. 56-127477 and Japanese Examined Utility Model Publication No. 60-14063.
In the flanged valve disclosed in the above Japanese Unexamined Utility Model Publication No. 56-127477, a body cap is provided with a flange integral therewith on the outer surface of an end thereof and provided with a plurality of projections on the outer surface of the other end thereof, a rib portion of a cap nut is provided with cut out portions allowing the projections to pass therethrough, thus the body cap and the cap nut can be engaged with each other.
In the flanged valve disclosed in the above Japanese Examined Utility Model Publication No. 60-14063, a body cap is provided with a flange integral therewith on the outer surface of an end thereof and provided with an annular groove on the outer surface adjacent to the other end thereof, and a cut out portion is provided on the outer surface of the body cap between the annular groove and the end face facing the valve body, while a split ring formed in a body and cut off at one point thereof is inserted into the annular groove from the cut out portion and thus engaged with the annular groove.
In the above flanged valves, each body cap having the flange integrally formed on the end thereof is engaged with the cap nut, and the cap nut is screwed on the outer surface of the valve body, thus these flanged valves are an improvement on the conventional flanged valves.
However, the above flanged valves have the following disadvantages.
In the flanged valve disclosed in Japanese Unexamined Utility Model Publication No. 56-12744, since the body cap and the cap nut when engaged are not in contact with the whole end surfaces of each other, the engaging strength between the body cap and the cap nut is decreased. In other words, the engaging strength between the body cap and the valve body is decreased. Further, manufacturing the projections and cut out portions is difficult.
In the flanged valve disclosed in Japanese Examined Utility Model Publication No. 60-14063, the engaging strength between the cap nut and body cap is increased. However, in order to fit the split ring into the annular groove, the large split ring must be flexed and deformed. Thus a special tool is required for this flexing and deforming, and assembling is difficult. Also, the same problems as mentioned above occur in the case of disassembling.